The van was found by a resident at a property in Dural in northwest Sydney.
A note reportedly found inside the van contained addresses of Jewish people and a synagogue and included the words, "f*** the Jews".
"That caravan contained an amount of explosives and some indication that those explosives might be used in some form of anti-Semitic attack," NSW Police Deputy Commissioner David Hudson said on Wednesday.
David Hudson says arrests have been made in connection to the discovery. (Steven Saphore/AAP PHOTOS)
Police are treating the incident as a credible terror threat and have assigned more than 100 counter-terrorism detectives to investigate those behind the plot, which was discovered on January 19.
Arrests had been made, with some connected to other alleged anti-Semitic attacks, Mr Hudson said.
"We have no information that there are further explosives in our community in relation to conducting anti-Semitic attacks anywhere - we believe that we have contained appropriately this current threat," he said.
The explosive material is believed to be power gel sourced from a mining site and could have resulted in a significant amount of damage with an explosion of 40m in diameter, the deputy commissioner said.
"We believe that through the arrests that have been made on the periphery of this job ... we've mitigated the risk as much as possible this stage," he said.
"I'm not saying it's been eliminated. I'm saying it's been mitigated."
Premier Chris Minns says the attack appeared to be a planned act of terrorism. (Steven Saphore/AAP PHOTOS)
NSW Premier Chris Minns was briefed on the incident on January 20 and promised to throw the state's resources to confront the threat to the community.
"This is the discovery of a potential mass casualty event. There's only one way of calling it out and that is terrorism," he said.
NSW Police was working with the Australian Federal Police, NSW Crime Commission, ASIO, Victoria Police and the Queensland Police Service to investigate the incident, Mr Hudson said.
There was no ongoing threat to the community, he said.
The incident comes after a spate of anti-Semitic attacks in Sydney, with a childcare centre near a synagogue in the city's east set alight and sprayed with anti-Semitic graffiti on January 21.
Statement from the NSW Premier. — Chris Minns (@ChrisMinnsMP) pic.twitter.com/OxHXuPCJ0mJanuary 29, 2025
Four days earlier, a house that formerly belonged to Executive Council of Australian Jewry co-chief executive Alex Ryvchin was targeted in an arson and graffiti attack.
Two men have been charged over a separate attack on a synagogue in Newtown after it was spray-painted with red swastikas and briefly set alight in the early hours of January 11.
Federal police have identified that foreign actors recruiting local "criminals for hire" could be behind some of the attacks targeting Jewish communities.
Cars have been set alight, a synagogue burnt down and anti-Semitic slurs painted on buildings and cars in attacks that have escalated in frequency and severity since December.
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